Thursday, August 15, 2013

Was the Early Universe a Cosmic Zoo?

The question, up until recently, was - how did the young universe appear?  Was it an orderly cross section of a few well mannered galaxies or was it a miss-mash of varied galactic types.

According to a recent article in, NASA's Hubble space telescope's "CANDLES" (Cosmic Assembly Near-Infrared Deep Extra-galactic Legacy Survey) study shows that the universe, even 11 billion years ago, "the diversity of galaxies in the early universe was as varied as the many galaxy types seen today"   This conclusion based on a galaxy classification system known as the Hubble Sequence of which CANDLES is a part.  The Sequence shows that the universe over the past 11 billion years was just as diverse as present day.

This becomes important when we look at how the Hubble Sequence is set up and the results that were garnered from the young universe.  The Sequence divides galaxies into three basic types based on their appearance:  Spiral which has plenty of gas for star building.  As the gas runs out galaxies transition to elliptical galaxies which are for all intents, blobs or middle aged to older.  In between Spiral and elliptical is the transitional lenticular galaxy which has a blob like bright center but also maintains some spiral arm structures.  The lenticular galaxies are middle aged.   What the Sequence is showing however is that all three galaxy types were in evidence in the young universe. 

From the article:
  • Arjen van der Wel of the Max Planck Institute for Astronomy in Heidelberg, Germany said "The galaxies look remarkably mature, which is not predicted by galaxy formation models to be the case that early on in the history of the universe."
  • While past research showed that these distinct types of galaxy morphology existed as early as 8 billion years ago, the new study extends that understanding back another 2.5 billion years.

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